Since human noses have a limited range of sizes and anatomical detail, typical intranasal airway (INA) devices are similar in size and conformity. Such devices may be used to increase nasal airflow, for filtering air, delivering medication, and for swimming Typical INA devices include a pair of cannulae having a cylindrical or frustoconical shape and may include filters, valves, hoses, etc.
Conventional INA devices have many disadvantages. One disadvantage is the insertion and removal of the INA device. For example, a cylindrical INA device may be more difficult to insert and more difficult to insert farther into the nasal passage, and, while a frustoconical INA device may be inserted easier and farther, it is at the expense of decreased airflow. Also, conventional INA devices are typically removed by pulling on a connecting portion that connects the cannulae. This is often uncomfortable as it drags the cannulae against the septum.
Another disadvantage is that INA devices, whether cylindrically or frustoconically shaped, are difficult to retain in place due to nasal mucous and the pressure of exhalation. Additionally, INA devices are typically manufactured to have some mechanism for maintaining their shape during use. This may include manufacture from a rigid or semi-rigid material or a rigid support inserted or integrated with a pliable material. Such mechanisms, while helping to maintain the shape of the INA device and helping maintain increased airflow, also increase the propensity of the INA device to become unintentionally dislodged from the nasal passage.
Some conventional INA devices address the problem of device retention through use of an external retention device such as a strap or clip that holds the INA device to the user's head or nose. Such retention devices (e.g., retention strap) are uncomfortable and interfere with the user's activities. Moreover, some external retention devices (e.g., retention clip) decrease airflow.
Another conventional method of addressing device retention is to form a protrusion on the outer surface of the cannulae of the device. For some conventional devices, such protrusions are directed toward the septum such that the protrusions on each cannula form a retaining clamp on the septum. Although, this helps to retain the INA device, it decreases airflow. Airflow is decreased because the protrusion causes a narrowing of the nasal passage, blocks a portion of the nasal passage used for airflow, and directs the aperture of each cannula inward, inhibiting airflow through the device to the nasal passage.
For other conventional devices, the retaining protrusions are directed away from the septum and toward the inner surface of the lateral portions of the nose. Again, while this protrusion scheme helps to retain the INA device, it decreases airflow by blocking a portion of the nasal passage used for airflow, and directing the aperture of each cannula outward toward the inner surface of the lateral portions of the nose which likewise inhibits airflow through the device to the nasal passage.
Another distinct disadvantage of conventional INA devises is that in attempting to promote their desired use of nasal airflow and promote device retention the device instead causes a degree of obstruction of the nasal passage resulting in decreased airflow by increasing the negative inhalation pressure which narrows the lumen of the nasal airways. The inclusion of such parts and retention protrusions compromise the lumen, thus resulting in reduced airflow. Some devices have a rim around the cannula. The rim is a uniform protrusion from the cannula with a generally annular shape. When pushed into the nostril the rim catches on the nasal concavities. Part of the rim will go into the anteromedial concavity and posterolateral concavity and the remainder of the rim will be pressed against the other portions of the interior of the nostril. See U.S. Pat. No. 8,833,369 to Dolezal, et al. While these devices provide device retention, because the rim is caught in the nostril, they provide only limited reduction of airflow impediments. Because the rim is of a general and uniform shape around the entire cannula the rim obstructs the nostril. Such devices increase the pressure against some portions of the nostril in an unnecessary and irritating manner Such pressure may reduce, rather than increase, airflow.
Other conventional devices may include a sponge-like seal that protrudes from the cannula. The seal is uniform around the cannula. This seal is compressible and when pushed into the nostril the compressible material expands to some degree into the anteromedial concavity and the posterolateral concavity and the remainder will remain compressed or become even more compressed as it is pressed against the other portions of the interior of the nostril. See U.S. Pat. No. 4,648,398 to Agdanowski, et al. The compressible material will expand to fill some areas of the nostril, depending on how far the device is inserted. But again, because of the uniform distribution of the compressible material prior to insertion, there will be uneven pressure against the nostril which may be irritating and may decrease airflow.
A distinct and major disadvantage of all prior art devices is that they fail to address the problems that arise when the nostrils, for various reasons are inadequate for the prevailing required airflow. Under such circumstances, a progressive accumulation of excessive negative inhalation pressure may occur. This may cause narrowing of the body's compliant airway. The increased negative pressure narrows the compliant airway and reduces nasal airflow. The restricted flow of ambient air may cause the user to inhale more forcefully and enter a cycle of increased negative inhalation pressure with an increase of the partial vacuum pressure on the compliant portions of the nasal passage which may decrease the level of available oxygen.